Endovascular prostheses are sometimes used to treat aortic aneurysms. Such treatment includes implanting a stent or stent-graft within the diseased vessel to bypass the anomaly. An aneurysm is a sac formed by the dilation of the wall of the artery. Aneurysms may be congenital, but are usually caused by disease or, occasionally, by trauma. Aortic aneurysms which commonly form between the renal arteries and the iliac arteries are referred to as abdominal aortic aneurysms (“AAAs”). Other aneurysms occur in the aorta, such as thoracic aortic aneurysms (“TAAs”), which may occur in one or more of the descending aorta, the ascending aorta, and the aortic arch.
Stent-grafts sometimes are implanted in patients having aneurysms close to or crossing branch openings to renal arteries or other branch arteries (e.g., the celiac artery, suprarenal artery, or superior or interior mesenteric arteries). Such stent-grafts have lateral openings avoid impairing blood flow from the aorta to these branching arteries from the aorta.